The presentation provides a brief overview of the technology employed to eliminate the power factor reduction caused by non linear loads in the network.

1. Analysis of Power Factor
Improvement Techniques in
Case of Non-Linear System
Loads
• Kaustubh Nande
• Abhinav Mitra
• Lalitesh Vaidyar
• Ritesh Ambadkar
(IIIrd Year, Electrical Engg., YCCE,Nagpur)

2. Definition:
The power factor of an AC electrical power
system is defined as the ratio of the real
power flowing to the load the apparent
power in the circuit.
• Power Factor plays a crucial role in the
economic operation of any system.
• Low power Factor implies low power
utilization, thereby reducing the system
efficiency.

3. • Low power factor shortens the lifespan of
electrical appliances.
• The heat dissipation in the system rises
proportionately by a factor equivalent to the
square of the current rise.
• Electricity Boards impose a surcharge to
customer if the power factor is <0.85.
• Also, Rebates are given to the customers if the
power factor is maintained >0.85.

4. Power factor improvement in case of linear loads
1. Using capacitor banks in parallel with the
system: The capacitance would try to
neutralise the inductance of the system
and thus the nature of the system tends
closer to being resistive, thereby
improving the power factor.
2. Using an synchronous condenser: An over
excited synchronous motor with no load
on it draws leading amperes, if the
condenser is connected in parallel with the
system, and thus improves the pf.
3. Using phase advancers: generally used for
an IM, the phase advancers, which is an
AC exciter provides exciting
amperes, which neutralise the lagging
stator amperes and improves the pf.

5. Power factor with non linear loads and sinusoidal voltage
•When the loads are non linear and current have harmonics pf cannot
be calculated using the traditional methods.
• I=I1
•pf=cos ϕ1 ×
Power factor will be function of displacement power factor and
distortion power factor.
Total power factor correction can only be achieved when both
displacement power factor and distortion power factor are corrected.
This requires a two step process:
1. Reduce the displacement angle between voltage and current.
2. Reduce the total harmonic current distortion.
If either of these steps is taken without the other the total power
factor will be increased but it may not be high enough to reach the
minimum value required by the utility.

6. Total power factor can be improved by decreasing the harmonic current distortion
• Using filter instead of capacitor bank.
• The capacitive part of the filter improves the displacement power factor,
while the combination of the reactor and the capacitor bank decrease the total
harmonic distortion of the current.
• At tuning harmonic filter act as capacitor bank and above it behaves as inductor. At the
tuning harmonic it behaves as a resistor.
.

7. The figure below shows the behaviour of the total power factor for different
values of displacement power factor and total harmonic current distortion.
pf=cos ϕ1 ×

8. Power Factor with non-linear loads
and voltage distortion.
• Traditional methods cannot be applied to
power calculation.
• Neglecting the phase angles of voltage
harmonics, voltage is given by
• Power factor is calculated as
××

9. • In the expression of power factor the term
p/sI is relation of total active power(including
harmonics) and fundamental power.
• The term is distortion power
factor pfdist
• Total power factor pf total is product of p/sI
and pfdist.

10. • Hence, when reactive power increases the
phase angles between fundamental
components of voltage and current increases,
hence, total power factor decreases.
• Due to distortion of voltage and current
increases, distortion power factor decreases,
total power factor decreases.

11. • So, to improve the power factor:-
1.Reduce the angle between fundamental
components of voltages and currents.
2.Reduce total harmonic distortion of
voltages and currents.

12. Vector relationship

13. • Phasor diagram shows the vector relationship
of P1,Q1F & S1F before power factor
improvement.
• For improvement a capacitor bank QCF is
added. But in case of using a capacitor bank
the resonance phenomena arises with main
transformer, which must be avoided.

14. • Use of harmonic filter improves the power
factor.
The capacitive part improves displacement
power factor and reactor & capacitor bank
combination decreases the
distortion, improving the distortion power
factor and total power factor as a whole.

15. HARMONIC FILTERS
(Frequency selective circuits)
An arrangement of linear electrical
elements(R,L,C) such that the circuit is
capable of attenuating one or more
frequencies depending on the values of R,L
and C.

16. TYPES
• Active Filters(used in low voltage systems)
• Passive Filters(used in medium and high
voltage systems)
ORDER OF THE FILTER = Number of energy
storage components used.

17. • usually connected in parallel with the system
• the frequency to be attenuated by a general
filter is a function of the filter parameters and
hence the filter can made to attenuate a large
number of frequencies by varying its
parameters.

18. The filters might again be classified as
• High pass filters
• Low pass filters
• All pass filters

19. Types
A. Series tuned filter
• intended to block the flow of harmonic
currents by providing a high harmonic series
impedence.
• passes the fundamental frequency only.

20. B. Single-tuned filter
• intended to greatly attenuate a single
harmonic component.The equation
that describes its impedance behavior
is
Zf =
• The tuning frequency of the single-
tuned
filter is adjusted by
f=1/2π√LC

21. C. First-order high-pass filter
• to achieve significant filtering to
reduce the harmonic
distortions, the capacitor size must
be notably large.
Z =

22. D. Second-order high-pass filter
• this filter is generally used as
a suppressor for several high-
order harmonics
Z =

23. E. Third-order high-pass filters
the capacitor C2 is also tuned
to the same
tuning frequency as the
capacitor C1 with the inductor.
Z =

24. F. C-type filters
• The C-type filter has an intermediate behavior
between the second- and third-order high-pass
filters. It exhibits no loss at the fundamental
frequency due to its topology. The capacitor C2 is
tuned, with the inductor,to the fundamental
frequency . This filter is usually utilized to filter
harmonics from a lower order than the two
previously explained filters.
Z =

25. Distribution static compensators
• Inject the pulses which are exactly 180
degrees out of phase of the unwanted
harmonics , thus cancelling out the unwanted
harmonics and yielding the output wave,very
close in nature to the fundamental wave

28. Conclusion
• Both the displacement and distortion power
factors need to be treated in order to maintain
good the total power factor.
• Harmonic filters attenuate the harmonic
frequencies and thus, an improved waveform is
obtained, thereby improving the overall power
factor.
• Certain other alternatives like Distribution static
compensators can also be used to eliminate the
harmonic components.

29. REFERENCES:
Power Factor in Electrical Power Systems
with Non-Linear Loads(Research thesis)
By: Gonzalo Sandoval
Passive Harmonic Filters for Medium-Voltage
Industrial Systems: Practical Considerations and
Topology Analysis
By:Alexandre B. Nassif

30. Thank You !